1108 F24 4.05 Sugar Transport in Plants via Phloem

Sugar Source

Any tissue producing or releasing sugar.

Sugar Sink

Any tissue using or storing sugar.

Translocation

Movement of sugars in phloem tissue.

Pressure Flow Model

Mechanism explaining sugar movement in phloem.

Solute Potential

Potential energy of solutes affecting water movement.

Pressure Potential

Physical pressure affecting fluid movement in plants.

Proton Pumps

Transport proteins creating hydrogen ion gradients.

Co-transporters

Proteins coupling solute transport across membranes.

Facilitated Diffusion

Passive transport of solutes via specific proteins.

Xylem

Tissue transporting water and minerals upward.

Phloem

Tissue transporting sugars and organic compounds.

Symporters

Transport proteins moving two solutes in same direction.

Antiporters

Transport proteins moving two solutes in opposite directions.

Sucrose Loading

Process of loading sucrose into phloem from sources.

Aphid Feeding

Insects extracting phloem sap using stylets.

Girdling Experiment

Removing bark to study phloem function.

Water Potential

Combined effect of solute and pressure potential.

Membrane Potential

Voltage difference across plant cell membranes.

Cation Uptake

Process driven by membrane potential for nutrient absorption.

Sap

Fluid containing sugars and nutrients in plants.

Sucrose Unloading

Release of sucrose into sink cells from phloem.

Hydrogen Ion Gradient

Difference in H+ concentration across membranes.

Pressure in Phloem

Internal pressure driving sap movement downward.

Concentration Gradient

Difference in solute concentration across a space.

Passive Transport

Movement of substances without energy input.

Active Transport

Movement of substances requiring energy (ATP).